Electrical connectors of the plug and receptacle type are used in many applications for connecting multiple pairs of corresponding conductors. Such connectors are widely used in the aerospace field in complex electronic systems in which a single connector may interconnect hundreds of pairs of wires. In such systems, the connectors must be miniaturized to minimize the weight and size. The wires at the receptacle are connected to individual terminals and the wires at the plug are connected to corresponding terminals. Each of the terminals on one of the connector members is a socket contact and each of the terminals on the other member is a pin contact which is adapted to telescopically engage the corresponding socket contact when the plug and receptacle are in mated relationship. In order to miniaturize the connector, the pin and socket contacts need to be very small; for example, the socket contact may be less than one-tenth inch diameter and less than one-half inch long.
Connectors of the type described must be capable of quick and easy connection and disconnection without undue force. Yet each set of contacts must provide excellent electrical conductivity and be capable of repeated connection and disconnection without damage or significant deterioration. When miniature contacts were first introduced, they were manufactured by machining from metal stock since that was the only feasible way to hold the tolerances required for the mating contacts. However, machined contacts are relatively costly. In recent years such contacts have been made from sheet metal by forming and rolling to produce a "formed" contact.
Formed socket contacts have been developed which comprise an assembly of a contact sleeve or liner of spring metal having plural contact fingers at the mating end and a supporting sleeve thereon. The wire receiving end is provided with plural openings and has a supporting sleeve thereon and is crimped into engagement with the wire. Additionally, a mounting flange is provided in the midsection of the contact sleeve. In this construction, the inner sleeve has an open seam from one end to the other, i.e. the abutting edges of the rolled sleeve are not welded or brazed together. A socket contact of this construction and method of making it are described in U.S. Pat. No. 4,072,394 granted Feb. 7, 1978 to Waldron et al. and assigned to the same assignee as this application. Formed contacts with welded or brazed seams are disclosed in the following patents: U.S. Pat. No. 3,286,223 granted Dec. 15, 1966 to Narozoni et al., U.S. Pat. No. 3,317,887 granted May 2, 1967 to Henschen et al., and U.S. Pat. No. 3,721,943 granted Mar. 20, 1973 to Curr.
In a socket contact of the type described, the contact fingers constitute cantilever beams deflected in a radial direction by the insertion of the mating pin contact. Each of the contact fingers is supported only at its root in the contact sleeve. In order to provide a requisite retention force on the pin contact by the socket contact and insure a good electrical connection, it is necessary to have each finger exert an appropriate resisting force to radial deflection.
In socket contacts of very small size, especially those with an outer diameter of about 0.06 inch, the contact fingers must be of very thin material. There has been a problem of obtaining the requisite retention force with contacts of this size.
A general object of this invention is to provide an improved socket contact which overcomes certain problems of the prior art.